It has just rained at the summit of Greenland’s ice sheet for the first time in recorded history, in yet another worrying milestone in our ecological unravelling.
Like much of the Northern Hemisphere, Greenland’s been experiencing a massive heatwave with temperatures at the glacier’s summit rising above freezing for the third time in less than a decade. On 14 August 2021, at a place normally far too frigid for water to fall as a liquid, the National Snow and Ice Data Center’s (NSIDC) Summit Station recorded several hours of rain.
“There is no previous report of rainfall at this location, which reaches 3,216 meters (10,551 feet) in elevation,” NSIDC reported, noting the amount of ice lost in one day was seven times more than the daily average for this time of year.
“Greenland, like the rest of the world, is changing,” University of Colorado Boulder glaciologist Ted Scambos told The Washington Post. “We now see three melting events in a decade in Greenland – and before 1990, that happened about once every 150 years. And now rainfall: in an area where rain never fell.”
“Like the heat wave in the [US Pacific] northwest, it’s something that’s hard to imagine without the influence of global climate change.”
Ice sheets form in areas of our planet that do not usually experience melt over the summer. Winter snow piles up over thousands of years, compressing under the weight of new layers.
Previous recent melts here have been caused by warm air temperatures alone, creating growing networks of summer lakes that can accelerate melting and destabilize the ice sheets.
Not only does rain melt snow, contributing to increasing melting events, it also has the added ability to mess with longer term ice sheet dynamics, too.
Rain exposes and freezes into a layer of ice that’s darker and therefore more heat absorbing than the usual white, packed-snow ice of the glacier. Once frozen it will also form a smooth barrier, preventing meltwater from seeping down below the surface. This can then flood the surface of the ice sheet, causing even more melting at higher elevations than runoff usually impacts.
“During melt events, these processes can occur over parts of the ice sheet that do not typically experience melt, making the impact more widespread,” NASA glaciologist Lauren Andrews said. “Positive feedbacks like these are starting to take their toll.”
The Greenland Ice Sheet holds enough freshwater to make sea levels rise 6 meters (20 feet), and has a large influence on weather and climate. The recent IPCC report warned exceeding 2 degrees Celsius of warming will trigger the collapse of this massive ice sheet. This is one of the major tipping points scientists are very concerned about.
Indigenous communities living in this region are facing challenges from loss of ice and wildlife are feeling the impacts of these changes, too. Beyond the direct impacts to sea level rise, meltwater from Greenland is also predicted to slow the Gulf Stream ocean current, which would alter patterns of tropical monsoons, impacting rainforests.
“We are crossing thresholds not seen in millennia, and frankly this is not going to change until we adjust what we’re doing to the air,” Scambos told CNN.
This will require many of us around the globe working together to hold those most responsible accountable, and helping each other make better collective choices.
Why did it rain at Greenland’s summit?
The island is estimated to have received a whopping 630 crore metric tonnes of rain in three days. According to the US National Snow and Ice Data Centre, this rain episode was among the heaviest recorded since 1950.
Warm, moist air blowing from the southwest of Greenland is likely to have triggered rains over the region. As per weather reports, a high air pressure formed over Greenland’s southeast and a marked low-pressure over Baffin Island in the west of the island around the same time.
Together, these meteorological conditions led to the prevalence of hot, moist air over Greenland. On August 14, temperatures at the ice sheet summit—at 3,216 metres high—crossed 0.48℃ for at least nine hours. As this temperature is above the freezing point, the precipitation occurred in the form of rain, explain scientists. Recorded data suggests that this is only the third time that Greenland recorded temperatures above the freezing point in the past decade.
(NASA/OIB)
Why is this rain a concern?
After Antarctica, Greenland hosts the world’s second-largest volume of ice sheets, and precipitation holds the potential to accelerate their melting process. The rains and warm temperatures between August 14 to 16 have also led to significant melting at the summit. Over these three days, the amount of ice loss was said to be seven times more than what happens typically during mid-August.
In the cold corner of the planet, the ice-covered landscape plays a huge role in escaping the impact of sunlight. Therefore, when rain falls on the ground, its warmth penetrates deeper and melts the ice cover. This, in turn, exposes the ground and leads to the absorption of more and more sunlight.
Greenland has already been facing the brunt of climate change. In July 2021, the region witnessed one of the most dramatic episodes of melting, where Greenland lost a whopping 8.5 billion tons of ice every day.
The recent report from the Intergovernmental Panel on Climate Change (IPCC) highlights that the carbon emissions from anthropogenic sources contributed significantly to the melting of the Greenland ice sheet over the past two decades. Hence, the entire episode underlines the importance of limiting greenhouse gas emissions to protect the pristine environment of the snowy paradise.
